二维码生成的WEB api方法

 /// <summary>
        /// 获取二维码
        /// </summary>
        /// <param name="size">编码测量度,值越大生成的二维码图片像素越高,尺寸越大（建议设置为4）</param>
        /// <returns></returns>
        [Route("ThirdParty/GetQRCode")]
        public HttpResponseMessage GetExamInfoQRCode( int size)
        {
            HttpResponseMessage message = new HttpResponseMessage();

            try
            {

                string Url = "www.baidu.com"

                //生成图片
                Bitmap image = CommonUtil.CreateImgQRCode(examInfoUrl, size);

                //保存图片数据
                MemoryStream stream = new MemoryStream();
                image.Save(stream, ImageFormat.Jpeg);
                message = Request.CreateResponse(HttpStatusCode.OK);
                message.Content = new ByteArrayContent(stream.ToArray());  //data为二进制图片数据
                message.Content.Headers.ContentType = new MediaTypeHeaderValue("image/png");

                return message;
            }
            catch (Exception ex)
            {
                //这里可以记录错误日志，然后返回一个默认的错误图片增强友好性
                message.Content = new ByteArrayContent(null);  //data为二进制图片数据
                message.Content.Headers.ContentType = new MediaTypeHeaderValue("image/png");
                return message;
            }

        }